Video: Extruding shapes

Now that I've got my 2D line, I'm ready to extrude it out in order to create a surface for my backdrop. So I will hit Alt+W and go out to Perspective view. And with my line selected, I will add an Extrude modifier. And Extrude just takes a line and makes it into a surface. When I add it, I have to immediately increase the amount because otherwise I won't actually see the surface if it has an Extrude amount of 0. So I will have to increase that. And I do want to make this fairly large as I mentioned before. So I am going to give it an Amount of 50 feet.

Extruding shapes

Now that I've got my 2D line, I'm ready to extrude it out in order to create asurface for my backdrop.So I will hit Alt+W and go out to Perspective view.And with my line selected, I will add an Extrude modifier.And Extrude just takes a line and makes it into a surface.When I add it, I have to immediately increase the amount because otherwise Iwon't actually see the surface if it has an Extrude amount of 0.So I will have to increase that.And I do want to make this fairly large as I mentioned before.So I am going to give it an Amount of 50 feet.

So type in 50' and then Enter.So that's the Extrude.You'll see it now being shown as black on our front side.If I orbit around to the back, you'll see green shaded on the backside, becauseit's got a green object color.Okay, well I am going to change that up.First of all, I am going to rename this.I am going to call this cyclorama.Press Enter and I want to change the object color too just so I am notdistracted by that green.I will choose a light gray and say OK.

But I am still getting blackness on one side.And the reason for this is that this extruded surface is one sided and thisbrings up an issue that you'll see a lot with polygon models having to do withthe surface being reversed.A more technical way of saying this is that the normals are flipped.A normal is a line that sticks out exactly perpendicular or orthogonally to asurface and if that normal is pointed towards the current view, in other words,if it's looking at me or at the camera then by default it's going to be renderable.

But if it's pointed away from the camera, then it's not renderable.To see this more dramatically, I'm going to turn on option called Back Face Culling.This is found in the Object Properties.You can get at Object Properties by using the right-click quad menu, and you'llsee it down here in the bottom of that quad menu, Object Properties, and I havean option here called Back Face Cull.I am going to turn that on so that you can see the effect of the normals being flipped.I will click OK and as I orbit around in here, you'll see from one side thesurface is invisible and from the other side it is visible.

So what I need to do is I just need to flip this surface or reverse the normals.So all I have got to do is add a modifier called Normal.So I will go down looking for that, Normal, and you will see that the Flipoption is on by default.So this just lets me choose which side I want to be renderable.And so I have got my backdrop.

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